If the leaves of the magnolia die off, pests or an illness are usually to blame. The most important magnolia diseases and pests are presented here.Magnolias are rarely affected
Diseases and pests rarely occur in magnolias. Nevertheless, there are one or the other disease that affects the magnolia, or some pests that occasionally tamper with the magnolia.
The most important diseases and pests include e.g. Leaf spots caused by Pseudomonas bacteria, mildew, whitefly and scale insects.
These diseases and pests affect magnolias
The bacterial leaf spot disease occurs with black spots, each surrounded by a yellow courtyard and bordered by the leaf veins. After a while, holes form in the center of the spots. Affected shoots of the magnolia can also die.
Pseudomonas bacteria spread mainly through raindrops and develop very well, especially under moist conditions. Accordingly, the foliage of the magnolia tree must be able to dry quickly for treatment. An airy location and a loose crown, a sufficient planting distance and no watering / water from above are helpful here.
Whites are only about 1.5 millimeters in size, but the insect can damage a magnolia. The whitefly deposits its approximately 0.5 millimeter long eggs on the underside of the leaves, from which the larvae hatch after some time. Nymphs and adult animals then feed on the leaf juice. The whitefly also deposits honeydew. This promotes the formation of mold and other fungal diseases so that leaves fall off and the fruits of other infected plants remain small.
In order to fight the whitefly effectively, natural enemies, such as the ladybird, are available. If their use does not help, you can use insecticides.
Mildew can be recognized by the typical whitish coating, which is located on the leaf surface and often also on the underside of the leaf. The clinical picture is caused by fungi that come from the Erysiphaceae family.
If there is an infestation with mildew, you can try to reduce it by taking various preventive measures. This includes, for example, that you ensure good exposure and that the plants are not too close together. However, if there is no improvement, you can also use a suitable plant protection product.
Like whiteflies, scale insects are plant juice suckers and also excrete honeydew.
Even if there is a scale insect infestation, you can first try natural enemies, such as ladybirds. Otherwise, a pesticide can help (see insect protection for plants).